1. Field of the Invention
This invention relates to surgical instruments and, more particularly, to instruments for preparing natural bone for receiving prosthetic components.
2. Description of the Prior Art
Many surgical techniques are known in the prior art for preparing the natural bones of a knee joint for receiving prosthetic components. Although the surgical techniques vary, the techniques provide a tibia and a femur with the resected surfaces shaped for receiving prosthetic components. In particular, the techniques vary in philosophical approaches to knee preparation, wherein the techniques vary by selecting either the tibia or femur to be initially prepared, applying different sequences in the order of surgical steps, and designating different resected surfaces as reference planes for preparing other resected surfaces. Additionally, surgical techniques vary with the type of prosthetic implantation being performed: primary implantation (first-time implantation) or revision implantation (replacement of failed or worn prosthetic components). It should be noted that there are rare instances where patients have seriously degenerated bones in the knee joint and require the application of the revision technique for primary implantation.
One technique for the primary implantation of prosthetic components in a knee is disclosed in a brochure entitled xe2x80x9cULTRA(trademark) Tricompartmental Knee Systemxe2x80x9d, containing a surgical procedure prepared by Frederick F. Buechel, M. D., and published by Biomedical Engineering Trust, 1998. Additionally, a technique used in revision implantation of a knee prosthesis is disclosed in a brochure entitled xe2x80x9cBuechel-Pappas(trademark) Modular Knee Revision System with Rebar(copyright) Screwsxe2x80x9d, containing a surgical procedure prepared by Frederick F. Buechel, M. D., and published by Biomedical Engineering Trust, January, 1998. The two aforementioned brochures are incorporated by reference herein for the description of these surgical techniques.
Due to the differences in techniques between primary and revision surgery, different surgical instruments are used with respect to each technique. Moreover, revision surgery requires a much greater number of instruments than primary surgery. To reduce the necessary number of instruments needed to be maintained in a operating room, efforts have been made in the prior art to combine multiple surgical functions into a single instrument or set of instruments. For example, the aforementioned surgical techniques both may utilize the surgical instruments, including the anterior-posterior femoral resection guide, described in U.S. Pat. No. 5,735,904 which issued on Apr. 7, 1998 to the inventor herein, entitled xe2x80x9cSPACER FOR ESTABLISHING PROSTHETIC GAP AND LIGAMENTOUS TENSIONxe2x80x9d. The disclosure of U.S. Pat. No. 5,735,904 is incorporated by reference herein. As disclosed in U.S. Pat. No. 5,735,904, the anterior-posterior femoral resection guide is provided with a fixed drill guide used in forming a pilot hole in the femur. As such, the anterior-posterior femoral resection guide efficiently serves two specific functions in addition to acting as a reference element in evaluating spacing between the tibia and the femur (as disclosed in U.S. Pat. No. 5,735,904): guidance for anterior and posterior resections of the femur; and guidance for drilling a pilot hole.
In revision surgery, a patient often requires the implantation of a stem into the femur to provide lateral stability to the prosthetic assembly in addition to the normal compressive loading applied thereto. The implantation of a stem, however, requires the formation of a channel in the femur through removal of bone. Typically, the channel is formed by first boring a 9 mm pilot hole into the distal end of the femur using a drill guide, such as that supported by the above-describe anterior-posterior femoral resection guide; removing the instrument supporting the pilot hole drill guide from the distal end of the femur; mounting a reaming guide; and sequentially using increasingly larger reamers to remove the soft inner bone of the femur and to eventually cut a cylindrical passage of predetermined length into the femoral endosteal cortex. In the prior art, a reamer guide or guides, separate from the drill guide and anterior-posterior femoral resection guide, are introduced to guide the reamers. However, the additional time and step of changing guides during surgery is undesired.
It is an object of the subject invention to provide a single set of instruments to prepare proper anterior and posterior femoral resections in primary surgery, as well as, revision surgery.
It is also an object of the subject invention to provide an anterior-posterior femoral resection guide with a set of detachable collets formed for guiding a drill, as well as, guiding various sized reamers.
The aforementioned objects are met by a set of instruments which includes an anterior-posterior femoral resection guide, and a set of collets formed to detachably mount onto the resection guide. Accordingly, the same set of instruments advantageously serves several functions both in primary and revision surgery.
The anterior-posterior femoral resection guide specifically has a generally rectangular body with planar anterior and posterior resection guide surfaces each formed to guide a prior art reciprocating saw in resecting anterior and posterior portions of a natural femur, respectively. Additionally, the resection guide has a guide aperture formed therethrough for interchangeably receiving the collets.
The set of collets includes a unitary tubular drill guide, preferably formed with a 9 mm inner passage, and a subset of reaming components, which, in turn, includes a unitary tubular reamer sleeve and a plurality of tubular reamer bushings. The reamer sleeve is formed to telescopically receive and accommodate each of the reamer bushings, and the reamer bushings are each shaped and formed to define a different inner diameter for accommodating a different sized reamer.
The drill guide and the reamer sleeve are formed to be directly detachably mounted to the guide aperture of the resection guide. It is preferred that a bayonet locking arrangement be utilized for achieving the direct detachable mounting. Particularly, the aperture of the resection guide is formed with a groove extending radially therefrom inset into the body of the resection guide, with two diametrically opposed recesses being formed in the body of the resection guide above the groove to create open passages thereto. Correspondingly, the drill guide and the reamer sleeve are each formed with diametrically opposed protruding ears dimensioned to pass through the recesses and slide into the groove upon being twisted.
For use during primary implantation, the resection guide of the subject invention is aligned and mounted onto the distal end of a femur. A yoke may be provided to align the anterior resection guide surface with the anterior femoral cortex. To align the resection guide, the resection guide is centered between the femoral epicondyles, and, preferably, the anterior resection guide surface is made level with the anterior femoral cortex. Once aligned, the resection guide is affixed to the femur using two or more bone pins. The drill guide is then mounted to the guide aperture, and a 9 mm channel, called a pilot hole, is bored into the femur using any prior art drilling instrument. An intramedullary rod is inserted through the drill guide and into the pilot hole. The yoke, if used, and the bone pins are then removed, and the instruments and techniques of U.S. Pat. No. 5,735,904 are preferably utilized to establish proper ligamentous tension between the femur and the tibia. After the proper ligamentous tension has been established, the femoral resection guide is once again rigidly fixed to the femur with the bone pins, and a reciprocating saw is used to perform anterior and posterior resections of the femur using the anterior and posterior resection guide surfaces, respectively.
For use during revision surgery, the resection guide of the subject invention is aligned relative to the distal end of the femur as described above with primary surgery, with the anterior resection guide surface being preferably level with the anterior femoral cortex, and the resection guide body being centered between the epicondyles of the femur. After the resection guide body is properly aligned and fixed to the femur using bone pins, the drill guide is mounted to the guide aperture, and a 9 mm pilot hole is drilled into the femur. Where a femoral stabilizing stem is required, the drill guide is removed and the reamer sleeve is attached to the guide aperture. Thereafter, a 10 mm reamer bushing is telescopically slipped into the reamer sleeve and a similar sized reamer is introduced to accordingly ream the pilot hole to 10 mm. Increasingly larger diameter reamer bushings and reamers are sequentially introduced to incrementally increase the diameter of the channel being formed in the femur. The surgeon completes the reaming process upon forming a cylindrical channel of predetermined length into the femoral endosteal cortex. A blunt-tipped reamer, having the same diameter as the final reamer, is then passed through the reamer bushing and into the reamed passage to act as an intramedullary rod. Subsequently, the yoke and bone pins are removed and, if necessary, the ligamentous tension is inspected. Also, the resection guide may be fixed to the femur to provide guidance for any necessary anterior and posterior resections.
As an additional feature, the reamer sleeve and reamer bushings can advantageously be used in cooperation with a tibial template to provide guidance in the reaming of a channel into the tibia.